1. Technical Field
The present invention relates to balls of ball valves, and more particularly, to a machine for grinding a spherical surface of a ball of a ball valve.
2. Description of Related Art
A ball of a ball valve is a spherical structure having a central flow channel and a grinding process is typically applied to a surface of the spherical structure to endow the same with a necessary surface smoothness. It is known that such grinding process can be performed with a belt sander by positioning a ball at a rotating shaft that rotates the ball and grinding a spherical surface of the ball with a high-speed running sand belt. However, when implemented to treat the spherical surface of the ball, the conventional belt sander having a physically planar grinding surface is incapable of ensuring a roundness of the ball. In addition, during the grinding process, relative displacement between the sand belt and the ball tends to form disordered grinding traces on the surface of the ball.
Besides, while the aforementioned grinding process is subject to professionals' manual operation, grinding dust generated during the grinding process can adversely affect the environment and the operators' health. Moreover, with a lack of a reliable way to ensure the roundness of the spherical structure of the ball, an accuracy of the roundness is confined to 20 μm, resulting in a limitation in the qualitative perfection of the ground balls.